The new ingredient of the model which we introduce here is the interaction of the stepped fluid with the dark matter.
During the time of radiation domination and well before the transition the momentum transfer rate scales as Hubble, \(\Gamma \propto H\) , and therefore remains equally important throughout this period.
Since in our model the WZDR fluid interacts with \(100\%\)  of the DM, similar to the study of [1]}, [2]},
the WZDR-DM coupling is weak and the momentum transfer rate is always smaller then Hubble.
As a result the DM does not oscillate but only experiences a friction as it falls into the gravitational potentials.
